Severance (Detail) (USD $) In Millions	3 Months Ended		12 Months Ended
	Aug. 31, 2011	Aug. 31, 2010	May 31, 2011	May 31, 2010
[Severance]	$ 3.3	$ 2.1	$ 6.7
Accrued Severance Cost	$ 2.4	$ 1.7	$ 1.9	$ 3.4